static bool probe_push_payload(probe_t * probe, size_t payload_size) {
layer_t * payload_layer,
* first_layer;
uint8_t * payload_bytes;
size_t packet_size;
// Check whether a payload is already set
if ((payload_layer = probe_get_layer_payload(probe))) {
fprintf(stderr, "Payload already set\n");
goto ERR_PAYLOAD_ALREADY_SET;
}
// Get the first protocol layer
if (!(first_layer = probe_get_layer(probe, 0))) {
fprintf(stderr, "No protocol layer defined in this probe\n");
goto ERR_NO_FIRST_LAYER;
}
// The first segment stores the packet size, thus:
// @payload = @first_segment + packet_size - payload_size
packet_size = probe_get_size(probe) ;
payload_bytes = packet_get_bytes(probe->packet) + packet_size - payload_size;
if (!(payload_layer = layer_create_from_segment(NULL, payload_bytes, payload_size))) {
goto ERR_LAYER_CREATE;
}
// Add the payload layer in the probe
if (!(probe_push_layer(probe, payload_layer))) {
fprintf(stderr, "Can't push payload layer\n");
goto ERR_PUSH_LAYER;
}
// Resize the payload if required
if (payload_size > 0) {
if (!probe_payload_resize(probe, payload_size)) {
fprintf(stderr, "Can't resize payload\n");
goto ERR_PAYLOAD_RESIZE;
}
}
return true;
ERR_PAYLOAD_RESIZE:
dynarray_del_ith_element(probe->layers, probe_get_num_layers(probe) - 1, NULL);
ERR_PUSH_LAYER:
layer_free(payload_layer);
ERR_LAYER_CREATE:
ERR_NO_FIRST_LAYER:
ERR_PAYLOAD_ALREADY_SET:
return false;
}
static probe_t * network_get_matching_probe(network_t * network, const probe_t * reply)
{
// Suppose we perform a traceroute measurement thanks to IPv4/UDP packet
// We encode in the IPv4 checksum the ID of the probe.
// Then, we should sniff an IPv4/ICMP/IPv4/UDP packet.
// The ICMP message carries the begining of our probe packet, so we can
// retrieve the checksum (= our probe ID) of the second IP layer, which
// corresponds to the 3rd checksum field of our probe.
uint16_t tag_probe, tag_reply;
probe_t * probe;
size_t i, num_flying_probes;
// XXX
// Fetch the tag from the reply. Its the 3rd checksum field.
if (!(reply_extract_tag(reply, &tag_reply))) {
// This is not an IP / ICMP / IP / * reply :(
if (network->is_verbose) fprintf(stderr, "Can't retrieve tag from reply\n");
return NULL;
}
num_flying_probes = dynarray_get_size(network->probes);
for (i = 0; i < num_flying_probes; i++) {
probe = dynarray_get_ith_element(network->probes, i);
// Reply / probe comparison. In our probe packet, the probe ID
// is stored in the checksum of the (first) IP layer.
if (probe_extract_tag(probe, &tag_probe)) {
if (tag_reply == tag_probe) break;
}
}
/*
// XXX BEGIN Harcoded ICMP response (JA 17/07/2014)
tag_reply = 0; tag_probe = 0; tag_probe++; tag_reply++;
num_flying_probes = dynarray_get_size(network->probes);
for (i = 0; i < num_flying_probes; i++) {
probe = dynarray_get_ith_element(network->probes, i);
// Reply / probe comparison. In our probe packet, the probe ID
// is stored in the checksum of the (first) IP layer.
if (probe_match((const struct probe_s *)probe, (const struct probe_s *)reply))
break;
}
// XXX END Hardcoded ICMP response
*/
// No match found if we reached the end of the array
if (i == num_flying_probes) {
if (network->is_verbose) {
fprintf(stderr, "network_get_matching_probe: This reply has been discarded: tag = 0x%x.\n", tag_reply);
network_flying_probes_dump(network);
}
return NULL;
}
// We delete the corresponding probe
// TODO: ... but it should be kept, for archive purposes, and to match for duplicates...
// But we cannot reenable it until we set the probe ID into the
// checksum, since probes with same flow_id and different TTL have the
// same checksum
dynarray_del_ith_element(network->probes, i, NULL);
// The matching probe is the oldest one and there are other probes, update
// the timer according to the next unexpired probe timeout.
if (i == 0) {
if (!(network_update_next_timeout(network))) {
fprintf(stderr, "Error while updating timeout\n");
}
}
return probe;
}